Many processes used in the chemical industry produce chemical waste, which at room temperature may be gaseous, liquid, or solid. There are many known methods to treat and discard gaseous and liquid waste. Treatment of gaseous waste, for obvious reasons is generally carried out at the point of their creation. Liquid waste can sometimes be carried out in the production facility, but very often the waste products are stored in containers and transported to another site for treatment. Waste that solidifies when held at ambient temperature (hereinafter solid waste) is also usually packed in containers that are then transported to special facilities for long-term storage or treatment such as by combusting in combustion plants. Disposal of this industrial chemical waste is very expensive since it requires special packaging materials, handling equipment, and storage areas. More importantly the present methods results in large quantities of harmful chemicals being stored each year around the world. The ecological problems both actual and potential caused by the disposal, transport, and storage of chemical waste are well know and, as a result of environmental protection treaties and laws and pressure exerted by oversight groups both governmental and private, considerable resources are expended by the chemical industry to treat the waste that is created as an unwanted byproduct of the production processes.
The term “neutralized” as used herein means the conversion of an ecologically harmful substance to a form that can be safely stored or released to the surroundings without causing damage to or being a threat to the environment. One of the most effective methods of neutralizing harmful chemical waste is high temperature pyrolysis of the raw waste material. As opposed to simply burning the waste, in a pyrolytic process the waste is reduced to atoms and ions, which upon cooling, react with each other and possibly other molecules and ions and recombine to form less harmful products that can be safely disposed of or used.
A typical arrangement for pyrolytic treatment of liquid chemical wastes is described in U.S. Pat. No. 4,644,877. In the apparatus described in this patent, the liquid waste is introduced directly into the interior zone of the cylindrical co-axial electrodes of a plasma torch. The waste material undergoes pyrolysis inside the torch. The resulting atoms and ions exit in the plasma stream into a reaction chamber where they begin to cool and recombine forming a mixture of gases and solid particles that pass to post-pyrolysis means where they are cooled and separated. The non-toxic gases are typically burned and either released to the atmosphere or used as fuel. The solid matter is disposed of in an unspecified manner.
U.S. Pat. No. 5,798,496 describes a portable waste disposal unit wherein a rotary kiln comprising at least one plasma gun and one or more movable target electrodes is mounted on a truck so that the unit can be easily transported to a waste site. The unit is designed to treat solid and/or liquid waste. Once the torch is activated to produce a plasma stream, the impedance in series with the torch anode is adjusted to create a “drawn arc” from the torch cathode to the one or more secondary anodes, thereby creating a hot zone in front of the plasma torch in which vitrification, pyrolysis, and gasification of the waste takes place.
It is a purpose of the invention to provide a plasma torch based processing system for converting hazardous fluid chemical waste into products that can either be reused or disposed of safely without creating a threat to the environment.
It is another purpose of the invention to provide a plasma torch based processing system that can be either permanently or temporarily attached to a process line in a chemical production facility for on-line treatment of the waste products as they are formed.
Further purposes and advantages of this invention will appear as the description proceeds.